Australian Patent No. 665,513 describes a vessel including a conical base used for mixing or dissolving a granular chemical in water. The vessel incorporates several elbow-shaped nozzles designed to direct the flow of water around the internal periphery of the vessel. The nozzles in combination with the conical base of the vessel create a circular flow of water in the vessel which is effective for dissolving the granular chemical. The water and granular chemical are recirculated through the vessel via a pump to promote dissolution of the granular chemical. Once the granular chemical is dissolved in the water, it is pumped to a boom spray tank or the like.
Where aggressive or corrosive chemicals are to be dissolved, the pump and valving must be constructed from materials which are compatible with these chemicals. For example, seals used in the pump and valve may need to be made of a suitable polymeric material, such as a VITON.RTM. material. Furthermore, the wetted internal parts of the pump and valves may need to be lined or constructed of a corrosion-resistant material, such as Type 316 stainless steel.
When used for mixing or dissolving particularly aggressive chemicals, even where the pump and valving are made of appropriate materials, frequent maintenance and replacement of parts is necessary. Pumps and valves constructed from compatible and corrosion-resistant materials are also generally expensive.